This is a small grant proposal to undertake the investigation of bipolar disorder (BP) in extended pedigrees in Costa Rica. Preliminary work has led to identification of two families that are potentially high informative for genetic interviews have been obtained for many members of these families. Also, lymphoblast cell lines have been established for 15 individuals. Collaborations have been established with investigators in Costa Rica. The specific goals of this proposal are to further characterize two Costa Rican pedigrees by systematic collection of family history information, pursuit of medial records, and diagnostic interviewing. Also, clinical populations in Costa Rica will be screened to identify additional promising pedigrees. Limited collection of pedigree and diagnostic information in these additional pedigrees will be performed to assess their potential informativeness for genetic linkage studies of BP. Lymphoblastoid cell lines will be established for individuals who are elderly, in poor health, or who will provide crucial information for the genetic analyses that will ultimately be carried our. The genetic 'identity' of these cell lines will be established through limited genotyping experiments using highly polymorphic DNA markers.